Specific Inhibition of Tumor Growth by T Cell Receptor-Drug Conjugates Targeting Intracellular Cancer-Testis Antigen NY-ESO-1/LAGE-1.

Despite the significant therapeutic advances in T-cell immunotherapy, many malignancies remain unresponsive, which might be because of the negative regulation of T cells by the tumor microenvironment (TME). T cells discriminate tumor cells and normal cells through T-cell receptors (TCRs); therefore, we generated a novel type of TCR-drug conjugates (TDCs) by referring antibody-drug conjugations (ADCs) to overcome the effects of the TME on T cells while preserving the specificity of TCR for tumor recognition. We selected HLA-A2/NY-ESO-1157-165 (peptide NY-ESO-1157-165 in complex with human leukocyte antigen serotype HLA-A*02:01) as the antigen and the antigen-specific TCR (1G4113) as the carrier. By sortase A-mediated ligation, we obtained three NY-TCR-vcMMAEs and further studied their properties, antitumor activity, and toxicity in vitro and in vivo. We found that all the NY-TCR-vcMMAEs had high endocytosis efficiency and specifically killed HLA-A2/NY-ESO-1157-165 positive tumor cells. In xenograft models, one of the TDCs, NY-TCR-2M, was effectively and specifically distributed into tumor tissues and inhibited tumor growth without inducing obvious toxicity. Our results demonstrated that TCRs can be carriers of toxic payloads and that the TDCs thus formed can specifically inhibit tumor growth, neglecting the immune microenvironment.

In situ quantitative bioanalysis of monomethyl auristatin E-conjugated antibody-drug conjugates by flow cytometry.

Antibody-drug conjugates (ADCs) consist of cytotoxic agents covalently conjugated to monoclonal antibodies that substantially improve antitumour activity and reduce systemic toxicity. With the growing number of ADCs in clinical applications, more accurate bioanalysis data are urgently needed to facilitate the development and rational use of ADCs. Herein, we used antigen-positive cells as antigen carriers and ofatumumab (OFA-HL) and ofatumumab-based ADC (OFA-HL-MMAE) as examples to establish a new ligand-binding assay (LBA) method based on flow cytometry. We proved that the new method met the required analytical performance criteria and the lower limit of quantitation (LOQ) was 0.2 µg/mL. In addition, the LOQ of the quantitative OFA-HL flow cytometry method was reduced to 0.025 µg/mL by choosing an optimized fluorescent antibody, which indicated that the LOQ of the new method can be improved. What's more, the new method showed good stability and specificity when we used it to determine the concentrations of OFA-HL and OFA-HL-MMAE in mouse serum. During the bioanalysis of ADCs, various factors should be considered. Therefore, choosing optimal methods for ADC bioanalysis is necessary. This new method using in situ antigens not only extends the scope of application of the conventional LBA methods by avoiding the need for soluble antigens, but also improves the authenticity of ADC bioanalysis as a supplementary approach, which is valuable for developing accurate ADC assays.